One U.S. study appearing Monday in the Archives of Ophthalmology found that those who smoke have nearly a twofold increased risk of age-related macular degeneration (AMD) compared to those who never smoke. There is also a higher risk for those who smoked in the past but quit.

    The study, conducted by Massachusetts Eye and Ear Infirmary in Boston, also found that seniors who eat fish at least twice weekly are almost half as likely to have AMD than those who eat fish less than once a week.

    In another study published in the same journal, Australian researchers reported a similar protective effect from omega-3 fatty acids, especially among those who ate two or more servings of fish per week, even when a history of smoking was taken into account.

    Macular degeneration is a disease in which the sharp central vision of the eye becomes blurred. It is the leading cause of blindness after age 60.

    The proper balance of essential fatty acids was crucial to preventing eye disease in the study, said Dr. Johanna Seddon of the Massachusetts Eye and Ear Infirmary in Boston, lead author of the U.S. study. The men who eat not only more omega-3 fatty acids, but also fewer omega-6 fatty acids, found in vegetable oils and baked goods, get the most benefit.

    Both studies on the effect of fish were based on participants' recall of what they ate. The studies were observational, meaning they observed people's behavior and health.

    Stronger evidence may come in five or six years with results from a large, randomized study, said Dr. Emily Chew of the National Eye Institute, who is heading the Australian study.

    Researchers don't yet know why eating fish seems to protect the eyes. Omega-3 fatty acids may neutralize free radicals in the eye, preventing the formation of new blood vessels, reducing inflammation or all three, Chew said. Enditem

    (Agencies)